src/librustc_resolve/build_reduced_graph.rs

   1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 //! Reduced graph building
  12 //!
  13 //! Here we build the "reduced graph": the graph of the module tree without
  14 //! any imports resolved.
  15
  16 use DefModifiers;
  17 use resolve_imports::ImportDirective;
  18 use resolve_imports::ImportDirectiveSubclass::{self, SingleImport, GlobImport};
  19 use resolve_imports::ImportResolution;
  20 use Module;
  21 use ModuleKind::*;
  22 use Namespace::{TypeNS, ValueNS};
  23 use NameBindings;
  24 use {names_to_string, module_to_string};
  25 use ParentLink::{self, ModuleParentLink, BlockParentLink};
  26 use Resolver;
  27 use resolve_imports::Shadowable;
  28 use TypeNsDef;
  29
  30 use self::DuplicateCheckingMode::*;
  31 use self::NamespaceError::*;
  32
  33 use rustc::metadata::csearch;
  34 use rustc::metadata::decoder::{DefLike, DlDef, DlField, DlImpl};
  35 use rustc::middle::def::*;
  36
  37 use syntax::ast::{Block, Crate};
  38 use syntax::ast::{DeclItem, DefId};
  39 use syntax::ast::{ForeignItem, ForeignItemFn, ForeignItemStatic};
  40 use syntax::ast::{Item, ItemConst, ItemEnum, ItemExternCrate, ItemFn};
  41 use syntax::ast::{ItemForeignMod, ItemImpl, ItemMac, ItemMod, ItemStatic, ItemDefaultImpl};
  42 use syntax::ast::{ItemStruct, ItemTrait, ItemTy, ItemUse};
  43 use syntax::ast::{Name, NamedField, NodeId};
  44 use syntax::ast::{PathListIdent, PathListMod, Public};
  45 use syntax::ast::StmtDecl;
  46 use syntax::ast::StructVariantKind;
  47 use syntax::ast::TupleVariantKind;
  48 use syntax::ast::UnnamedField;
  49 use syntax::ast::{Variant, ViewPathGlob, ViewPathList, ViewPathSimple};
  50 use syntax::ast::Visibility;
  51 use syntax::ast;
  52 use syntax::ast_util::local_def;
  53 use syntax::attr::AttrMetaMethods;
  54 use syntax::parse::token::{self, special_idents};
  55 use syntax::codemap::{Span, DUMMY_SP};
  56 use syntax::visit::{self, Visitor};
  57
  58 use std::mem::replace;
  59 use std::ops::{Deref, DerefMut};
  60 use std::rc::Rc;
  61
  62 // Specifies how duplicates should be handled when adding a child item if
  63 // another item exists with the same name in some namespace.
  64 #[derive(Copy, Clone, PartialEq)]
  65 enum DuplicateCheckingMode {
  66     ForbidDuplicateModules,
  67     ForbidDuplicateTypesAndModules,
  68     ForbidDuplicateValues,
  69     ForbidDuplicateTypesAndValues,
  70     OverwriteDuplicates
  71 }
  72
  73 #[derive(Copy, Clone, PartialEq)]
  74 enum NamespaceError {
  75     NoError,
  76     ModuleError,
  77     TypeError,
  78     ValueError
  79 }
  80
  81 fn namespace_error_to_string(ns: NamespaceError) -> &'static str {
  82     match ns {
  83         NoError                 => "",
  84         ModuleError | TypeError => "type or module",
  85         ValueError              => "value",
  86     }
  87 }
  88
  89 struct GraphBuilder<'a, 'b:'a, 'tcx:'b> {
  90     resolver: &'a mut Resolver<'b, 'tcx>
  91 }
  92
  93 impl<'a, 'b:'a, 'tcx:'b> Deref for GraphBuilder<'a, 'b, 'tcx> {
  94     type Target = Resolver<'b, 'tcx>;
  95
  96     fn deref(&self) -> &Resolver<'b, 'tcx> {
  97         &*self.resolver
  98     }
  99 }
 100
 101 impl<'a, 'b:'a, 'tcx:'b> DerefMut for GraphBuilder<'a, 'b, 'tcx> {
 102     fn deref_mut(&mut self) -> &mut Resolver<'b, 'tcx> {
 103         &mut *self.resolver
 104     }
 105 }
 106
 107 impl<'a, 'b:'a, 'tcx:'b> GraphBuilder<'a, 'b, 'tcx> {
 108     /// Constructs the reduced graph for the entire crate.
 109     fn build_reduced_graph(self, krate: &ast::Crate) {
 110         let parent = self.graph_root.get_module();
 111         let mut visitor = BuildReducedGraphVisitor {
 112             builder: self,
 113             parent: parent
 114         };
 115         visit::walk_crate(&mut visitor, krate);
 116     }
 117
 118     /// Adds a new child item to the module definition of the parent node and
 119     /// returns its corresponding name bindings as well as the current parent.
 120     /// Or, if we're inside a block, creates (or reuses) an anonymous module
 121     /// corresponding to the innermost block ID and returns the name bindings
 122     /// as well as the newly-created parent.
 123     ///
 124     /// # Panics
 125     ///
 126     /// Panics if this node does not have a module definition and we are not inside
 127     /// a block.
 128     fn add_child(&self,
 129                  name: Name,
 130                  parent: &Rc<Module>,
 131                  duplicate_checking_mode: DuplicateCheckingMode,
 132                  // For printing errors
 133                  sp: Span)
 134                  -> Rc<NameBindings> {
 135         // If this is the immediate descendant of a module, then we add the
 136         // child name directly. Otherwise, we create or reuse an anonymous
 137         // module and add the child to that.
 138
 139         self.check_for_conflicts_between_external_crates_and_items(&**parent,
 140                                                                    name,
 141                                                                    sp);
 142
 143         // Add or reuse the child.
 144         let child = parent.children.borrow().get(&name).cloned();
 145         match child {
 146             None => {
 147                 let child = Rc::new(NameBindings::new());
 148                 parent.children.borrow_mut().insert(name, child.clone());
 149                 child
 150             }
 151             Some(child) => {
 152                 // Enforce the duplicate checking mode:
 153                 //
 154                 // * If we're requesting duplicate module checking, check that
 155                 //   there isn't a module in the module with the same name.
 156                 //
 157                 // * If we're requesting duplicate type checking, check that
 158                 //   there isn't a type in the module with the same name.
 159                 //
 160                 // * If we're requesting duplicate value checking, check that
 161                 //   there isn't a value in the module with the same name.
 162                 //
 163                 // * If we're requesting duplicate type checking and duplicate
 164                 //   value checking, check that there isn't a duplicate type
 165                 //   and a duplicate value with the same name.
 166                 //
 167                 // * If no duplicate checking was requested at all, do
 168                 //   nothing.
 169
 170                 let mut duplicate_type = NoError;
 171                 let ns = match duplicate_checking_mode {
 172                     ForbidDuplicateModules => {
 173                         if child.get_module_if_available().is_some() {
 174                             duplicate_type = ModuleError;
 175                         }
 176                         Some(TypeNS)
 177                     }
 178                     ForbidDuplicateTypesAndModules => {
 179                         if child.defined_in_namespace(TypeNS) {
 180                             duplicate_type = TypeError;
 181                         }
 182                         Some(TypeNS)
 183                     }
 184                     ForbidDuplicateValues => {
 185                         if child.defined_in_namespace(ValueNS) {
 186                             duplicate_type = ValueError;
 187                         }
 188                         Some(ValueNS)
 189                     }
 190                     ForbidDuplicateTypesAndValues => {
 191                         let mut n = None;
 192                         match child.def_for_namespace(TypeNS) {
 193                             Some(DefMod(_)) | None => {}
 194                             Some(_) => {
 195                                 n = Some(TypeNS);
 196                                 duplicate_type = TypeError;
 197                             }
 198                         };
 199                         if child.defined_in_namespace(ValueNS) {
 200                             duplicate_type = ValueError;
 201                             n = Some(ValueNS);
 202                         }
 203                         n
 204                     }
 205                     OverwriteDuplicates => None
 206                 };
 207                 if duplicate_type != NoError {
 208                     // Return an error here by looking up the namespace that
 209                     // had the duplicate.
 210                     let ns = ns.unwrap();
 211                     resolve_err!(self, sp, E0428,
 212                                  "duplicate definition of {} `{}`",
 213                                  namespace_error_to_string(duplicate_type),
 214                                  token::get_name(name));
 215                     {
 216                         let r = child.span_for_namespace(ns);
 217                         if let Some(sp) = r {
 218                             self.session.span_note(sp,
 219                                  &format!("first definition of {} `{}` here",
 220                                       namespace_error_to_string(duplicate_type),
 221                                       token::get_name(name)));
 222                         }
 223                     }
 224                 }
 225                 child
 226             }
 227         }
 228     }
 229
 230     fn block_needs_anonymous_module(&mut self, block: &Block) -> bool {
 231         // Check each statement.
 232         for statement in &block.stmts {
 233             match statement.node {
 234                 StmtDecl(ref declaration, _) => {
 235                     match declaration.node {
 236                         DeclItem(_) => {
 237                             return true;
 238                         }
 239                         _ => {
 240                             // Keep searching.
 241                         }
 242                     }
 243                 }
 244                 _ => {
 245                     // Keep searching.
 246                 }
 247             }
 248         }
 249
 250         // If we found no items, we don't need to create
 251         // an anonymous module.
 252
 253         return false;
 254     }
 255
 256     fn get_parent_link(&mut self, parent: &Rc<Module>, name: Name) -> ParentLink {
 257         ModuleParentLink(parent.downgrade(), name)
 258     }
 259
 260     /// Constructs the reduced graph for one item.
 261     fn build_reduced_graph_for_item(&mut self, item: &Item, parent: &Rc<Module>) -> Rc<Module> {
 262         let name = item.ident.name;
 263         let sp = item.span;
 264         let is_public = item.vis == ast::Public;
 265         let modifiers = if is_public {
 266             DefModifiers::PUBLIC
 267         } else {
 268             DefModifiers::empty()
 269         } | DefModifiers::IMPORTABLE;
 270
 271         match item.node {
 272             ItemUse(ref view_path) => {
 273                 // Extract and intern the module part of the path. For
 274                 // globs and lists, the path is found directly in the AST;
 275                 // for simple paths we have to munge the path a little.
 276                 let module_path = match view_path.node {
 277                     ViewPathSimple(_, ref full_path) => {
 278                         full_path.segments
 279                             .init()
 280                             .iter().map(|ident| ident.identifier.name)
 281                             .collect()
 282                     }
 283
 284                     ViewPathGlob(ref module_ident_path) |
 285                     ViewPathList(ref module_ident_path, _) => {
 286                         module_ident_path.segments
 287                             .iter().map(|ident| ident.identifier.name).collect()
 288                     }
 289                 };
 290
 291                 // Build up the import directives.
 292                 let shadowable = item.attrs.iter().any(|attr| {
 293                     attr.name() == token::get_name(special_idents::prelude_import.name)
 294                 });
 295                 let shadowable = if shadowable {
 296                     Shadowable::Always
 297                 } else {
 298                     Shadowable::Never
 299                 };
 300
 301                 match view_path.node {
 302                     ViewPathSimple(binding, ref full_path) => {
 303                         let source_name =
 304                             full_path.segments.last().unwrap().identifier.name;
 305                         if &token::get_name(source_name)[..] == "mod" ||
 306                            &token::get_name(source_name)[..] == "self" {
 307                             resolve_err!(self, view_path.span, E0429,
 308                                          "{}",
 309                                          "`self` imports are only allowed within a { } list");
 310                         }
 311
 312                         let subclass = SingleImport(binding.name,
 313                                                     source_name);
 314                         self.build_import_directive(&**parent,
 315                                                     module_path,
 316                                                     subclass,
 317                                                     view_path.span,
 318                                                     item.id,
 319                                                     is_public,
 320                                                     shadowable);
 321                     }
 322                     ViewPathList(_, ref source_items) => {
 323                         // Make sure there's at most one `mod` import in the list.
 324                         let mod_spans = source_items.iter().filter_map(|item| match item.node {
 325                             PathListMod { .. } => Some(item.span),
 326                             _ => None
 327                         }).collect::<Vec<Span>>();
 328                         if mod_spans.len() > 1 {
 329                             resolve_err!(self, mod_spans[0], E0430,
 330                                          "{}",
 331                                          "`self` import can only appear once in the list");
 332                             for other_span in mod_spans.iter().skip(1) {
 333                                 self.session.span_note(*other_span,
 334                                     "another `self` import appears here");
 335                             }
 336                         }
 337
 338                         for source_item in source_items {
 339                             let (module_path, name) = match source_item.node {
 340                                 PathListIdent { name, .. } =>
 341                                     (module_path.clone(), name.name),
 342                                 PathListMod { .. } => {
 343                                     let name = match module_path.last() {
 344                                         Some(name) => *name,
 345                                         None => {
 346                                             resolve_err!(self, source_item.span, E0431,
 347                                                 "{}",
 348                                                 "`self` import can only appear in an import list \
 349                                                  with a non-empty prefix");
 350                                             continue;
 351                                         }
 352                                     };
 353                                     let module_path = module_path.init();
 354                                     (module_path.to_vec(), name)
 355                                 }
 356                             };
 357                             self.build_import_directive(
 358                                 &**parent,
 359                                 module_path,
 360                                 SingleImport(name, name),
 361                                 source_item.span,
 362                                 source_item.node.id(),
 363                                 is_public,
 364                                 shadowable);
 365                         }
 366                     }
 367                     ViewPathGlob(_) => {
 368                         self.build_import_directive(&**parent,
 369                                                     module_path,
 370                                                     GlobImport,
 371                                                     view_path.span,
 372                                                     item.id,
 373                                                     is_public,
 374                                                     shadowable);
 375                     }
 376                 }
 377                 parent.clone()
 378             }
 379
 380             ItemExternCrate(_) => {
 381                 // n.b. we don't need to look at the path option here, because cstore already did
 382                 if let Some(crate_id) = self.session.cstore.find_extern_mod_stmt_cnum(item.id) {
 383                     let def_id = DefId { krate: crate_id, node: 0 };
 384                     self.external_exports.insert(def_id);
 385                     let parent_link = ModuleParentLink(parent.downgrade(), name);
 386                     let external_module = Rc::new(Module::new(parent_link,
 387                                                               Some(def_id),
 388                                                               NormalModuleKind,
 389                                                               false,
 390                                                               true));
 391                     debug!("(build reduced graph for item) found extern `{}`",
 392                             module_to_string(&*external_module));
 393                     self.check_for_conflicts_between_external_crates(&**parent, name, sp);
 394                     parent.external_module_children.borrow_mut()
 395                           .insert(name, external_module.clone());
 396                     self.build_reduced_graph_for_external_crate(&external_module);
 397                 }
 398                 parent.clone()
 399             }
 400
 401             ItemMod(..) => {
 402                 let name_bindings = self.add_child(name, parent, ForbidDuplicateModules, sp);
 403
 404                 let parent_link = self.get_parent_link(parent, name);
 405                 let def_id = DefId { krate: 0, node: item.id };
 406                 name_bindings.define_module(parent_link,
 407                                             Some(def_id),
 408                                             NormalModuleKind,
 409                                             false,
 410                                             is_public,
 411                                             sp);
 412
 413                 name_bindings.get_module()
 414             }
 415
 416             ItemForeignMod(..) => parent.clone(),
 417
 418             // These items live in the value namespace.
 419             ItemStatic(_, m, _) => {
 420                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 421                 let mutbl = m == ast::MutMutable;
 422
 423                 name_bindings.define_value(DefStatic(local_def(item.id), mutbl), sp, modifiers);
 424                 parent.clone()
 425             }
 426             ItemConst(_, _) => {
 427                 self.add_child(name, parent, ForbidDuplicateValues, sp)
 428                     .define_value(DefConst(local_def(item.id)), sp, modifiers);
 429                 parent.clone()
 430             }
 431             ItemFn(_, _, _, _, _, _) => {
 432                 let name_bindings = self.add_child(name, parent, ForbidDuplicateValues, sp);
 433
 434                 let def = DefFn(local_def(item.id), false);
 435                 name_bindings.define_value(def, sp, modifiers);
 436                 parent.clone()
 437             }
 438
 439             // These items live in the type namespace.
 440             ItemTy(..) => {
 441                 let name_bindings =
 442                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 443
 444                 name_bindings.define_type(DefTy(local_def(item.id), false), sp,
 445                                           modifiers);
 446
 447                 let parent_link = self.get_parent_link(parent, name);
 448                 name_bindings.set_module_kind(parent_link,
 449                                               Some(local_def(item.id)),
 450                                               TypeModuleKind,
 451                                               false,
 452                                               is_public,
 453                                               sp);
 454                 parent.clone()
 455             }
 456
 457             ItemEnum(ref enum_definition, _) => {
 458                 let name_bindings =
 459                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 460
 461                 name_bindings.define_type(DefTy(local_def(item.id), true), sp, modifiers);
 462
 463                 let parent_link = self.get_parent_link(parent, name);
 464                 name_bindings.set_module_kind(parent_link,
 465                                               Some(local_def(item.id)),
 466                                               EnumModuleKind,
 467                                               false,
 468                                               is_public,
 469                                               sp);
 470
 471                 let module = name_bindings.get_module();
 472
 473                 for variant in &(*enum_definition).variants {
 474                     self.build_reduced_graph_for_variant(
 475                         &**variant,
 476                         local_def(item.id),
 477                         &module);
 478                 }
 479                 parent.clone()
 480             }
 481
 482             // These items live in both the type and value namespaces.
 483             ItemStruct(ref struct_def, _) => {
 484                 // Adding to both Type and Value namespaces or just Type?
 485                 let (forbid, ctor_id) = match struct_def.ctor_id {
 486                     Some(ctor_id)   => (ForbidDuplicateTypesAndValues, Some(ctor_id)),
 487                     None            => (ForbidDuplicateTypesAndModules, None)
 488                 };
 489
 490                 let name_bindings = self.add_child(name, parent, forbid, sp);
 491
 492                 // Define a name in the type namespace.
 493                 name_bindings.define_type(DefTy(local_def(item.id), false), sp, modifiers);
 494
 495                 // If this is a newtype or unit-like struct, define a name
 496                 // in the value namespace as well
 497                 if let Some(cid) = ctor_id {
 498                     name_bindings.define_value(DefStruct(local_def(cid)), sp, modifiers);
 499                 }
 500
 501                 // Record the def ID and fields of this struct.
 502                 let named_fields = struct_def.fields.iter().filter_map(|f| {
 503                     match f.node.kind {
 504                         NamedField(ident, _) => Some(ident.name),
 505                         UnnamedField(_) => None
 506                     }
 507                 }).collect();
 508                 self.structs.insert(local_def(item.id), named_fields);
 509
 510                 parent.clone()
 511             }
 512
 513             ItemDefaultImpl(_, _) |
 514             ItemImpl(..) => parent.clone(),
 515
 516             ItemTrait(_, _, _, ref items) => {
 517                 let name_bindings =
 518                     self.add_child(name, parent, ForbidDuplicateTypesAndModules, sp);
 519
 520                 // Add all the items within to a new module.
 521                 let parent_link = self.get_parent_link(parent, name);
 522                 name_bindings.define_module(parent_link,
 523                                             Some(local_def(item.id)),
 524                                             TraitModuleKind,
 525                                             false,
 526                                             is_public,
 527                                             sp);
 528                 let module_parent = name_bindings.get_module();
 529
 530                 let def_id = local_def(item.id);
 531
 532                 // Add the names of all the items to the trait info.
 533                 for trait_item in items {
 534                     let name_bindings = self.add_child(trait_item.ident.name,
 535                                         &module_parent,
 536                                         ForbidDuplicateTypesAndValues,
 537                                         trait_item.span);
 538
 539                     match trait_item.node {
 540                         ast::ConstTraitItem(..) => {
 541                             let def = DefAssociatedConst(local_def(trait_item.id),
 542                                                          FromTrait(local_def(item.id)));
 543                             // NB: not DefModifiers::IMPORTABLE
 544                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 545                         }
 546                         ast::MethodTraitItem(..) => {
 547                             let def = DefMethod(local_def(trait_item.id),
 548                                                 FromTrait(local_def(item.id)));
 549                             // NB: not DefModifiers::IMPORTABLE
 550                             name_bindings.define_value(def, trait_item.span, DefModifiers::PUBLIC);
 551                         }
 552                         ast::TypeTraitItem(..) => {
 553                             let def = DefAssociatedTy(local_def(item.id),
 554                                                       local_def(trait_item.id));
 555                             // NB: not DefModifiers::IMPORTABLE
 556                             name_bindings.define_type(def, trait_item.span, DefModifiers::PUBLIC);
 557                         }
 558                     }
 559
 560                     self.trait_item_map.insert((trait_item.ident.name, def_id),
 561                                                local_def(trait_item.id));
 562                 }
 563
 564                 name_bindings.define_type(DefTrait(def_id), sp, modifiers);
 565                 parent.clone()
 566             }
 567             ItemMac(..) => parent.clone()
 568         }
 569     }
 570
 571     // Constructs the reduced graph for one variant. Variants exist in the
 572     // type and value namespaces.
 573     fn build_reduced_graph_for_variant(&mut self,
 574                                        variant: &Variant,
 575                                        item_id: DefId,
 576                                        parent: &Rc<Module>) {
 577         let name = variant.node.name.name;
 578         let is_exported = match variant.node.kind {
 579             TupleVariantKind(_) => false,
 580             StructVariantKind(_) => {
 581                 // Not adding fields for variants as they are not accessed with a self receiver
 582                 self.structs.insert(local_def(variant.node.id), Vec::new());
 583                 true
 584             }
 585         };
 586
 587         let child = self.add_child(name, parent,
 588                                    ForbidDuplicateTypesAndValues,
 589                                    variant.span);
 590         // variants are always treated as importable to allow them to be glob
 591         // used
 592         child.define_value(DefVariant(item_id,
 593                                       local_def(variant.node.id), is_exported),
 594                            variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 595         child.define_type(DefVariant(item_id,
 596                                      local_def(variant.node.id), is_exported),
 597                           variant.span, DefModifiers::PUBLIC | DefModifiers::IMPORTABLE);
 598     }
 599
 600     /// Constructs the reduced graph for one foreign item.
 601     fn build_reduced_graph_for_foreign_item(&mut self,
 602                                             foreign_item: &ForeignItem,
 603                                             parent: &Rc<Module>) {
 604         let name = foreign_item.ident.name;
 605         let is_public = foreign_item.vis == ast::Public;
 606         let modifiers = if is_public {
 607             DefModifiers::PUBLIC
 608         } else {
 609             DefModifiers::empty()
 610         } | DefModifiers::IMPORTABLE;
 611         let name_bindings =
 612             self.add_child(name, parent, ForbidDuplicateValues,
 613                            foreign_item.span);
 614
 615         let def = match foreign_item.node {
 616             ForeignItemFn(..) => {
 617                 DefFn(local_def(foreign_item.id), false)
 618             }
 619             ForeignItemStatic(_, m) => {
 620                 DefStatic(local_def(foreign_item.id), m)
 621             }
 622         };
 623         name_bindings.define_value(def, foreign_item.span, modifiers);
 624     }
 625
 626     fn build_reduced_graph_for_block(&mut self, block: &Block, parent: &Rc<Module>) -> Rc<Module> {
 627         if self.block_needs_anonymous_module(block) {
 628             let block_id = block.id;
 629
 630             debug!("(building reduced graph for block) creating a new \
 631                     anonymous module for block {}",
 632                    block_id);
 633
 634             let new_module = Rc::new(Module::new(
 635                 BlockParentLink(parent.downgrade(), block_id),
 636                 None,
 637                 AnonymousModuleKind,
 638                 false,
 639                 false));
 640             parent.anonymous_children.borrow_mut().insert(block_id, new_module.clone());
 641             new_module
 642         } else {
 643             parent.clone()
 644         }
 645     }
 646
 647     fn handle_external_def(&mut self,
 648                            def: Def,
 649                            vis: Visibility,
 650                            child_name_bindings: &NameBindings,
 651                            final_ident: &str,
 652                            name: Name,
 653                            new_parent: &Rc<Module>) {
 654         debug!("(building reduced graph for \
 655                 external crate) building external def {}, priv {:?}",
 656                final_ident, vis);
 657         let is_public = vis == ast::Public;
 658         let modifiers = if is_public {
 659             DefModifiers::PUBLIC
 660         } else {
 661             DefModifiers::empty()
 662         } | DefModifiers::IMPORTABLE;
 663         let is_exported = is_public && match new_parent.def_id.get() {
 664             None => true,
 665             Some(did) => self.external_exports.contains(&did)
 666         };
 667         if is_exported {
 668             self.external_exports.insert(def.def_id());
 669         }
 670
 671         let kind = match def {
 672             DefTy(_, true) => EnumModuleKind,
 673             DefTy(_, false) | DefStruct(..) => TypeModuleKind,
 674             _ => NormalModuleKind
 675         };
 676
 677         match def {
 678           DefMod(def_id) | DefForeignMod(def_id) | DefStruct(def_id) |
 679           DefTy(def_id, _) => {
 680             let type_def = child_name_bindings.type_def.borrow().clone();
 681             match type_def {
 682               Some(TypeNsDef { module_def: Some(module_def), .. }) => {
 683                 debug!("(building reduced graph for external crate) \
 684                         already created module");
 685                 module_def.def_id.set(Some(def_id));
 686               }
 687               Some(_) | None => {
 688                 debug!("(building reduced graph for \
 689                         external crate) building module \
 690                         {} {}", final_ident, is_public);
 691                 let parent_link = self.get_parent_link(new_parent, name);
 692
 693                 child_name_bindings.define_module(parent_link,
 694                                                   Some(def_id),
 695                                                   kind,
 696                                                   true,
 697                                                   is_public,
 698                                                   DUMMY_SP);
 699               }
 700             }
 701           }
 702           _ => {}
 703         }
 704
 705         match def {
 706           DefMod(_) | DefForeignMod(_) => {}
 707           DefVariant(_, variant_id, is_struct) => {
 708               debug!("(building reduced graph for external crate) building \
 709                       variant {}",
 710                       final_ident);
 711               // variants are always treated as importable to allow them to be
 712               // glob used
 713               let modifiers = DefModifiers::PUBLIC | DefModifiers::IMPORTABLE;
 714               if is_struct {
 715                   child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 716                   // Not adding fields for variants as they are not accessed with a self receiver
 717                   self.structs.insert(variant_id, Vec::new());
 718               } else {
 719                   child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 720               }
 721           }
 722           DefFn(ctor_id, true) => {
 723             child_name_bindings.define_value(
 724                 csearch::get_tuple_struct_definition_if_ctor(&self.session.cstore, ctor_id)
 725                     .map_or(def, |_| DefStruct(ctor_id)), DUMMY_SP, modifiers);
 726           }
 727           DefFn(..) | DefStatic(..) | DefConst(..) | DefAssociatedConst(..) |
 728           DefMethod(..) => {
 729             debug!("(building reduced graph for external \
 730                     crate) building value (fn/static) {}", final_ident);
 731             // impl methods have already been defined with the correct importability modifier
 732             let mut modifiers = match *child_name_bindings.value_def.borrow() {
 733                 Some(ref def) => (modifiers & !DefModifiers::IMPORTABLE) |
 734                              (def.modifiers &  DefModifiers::IMPORTABLE),
 735                 None => modifiers
 736             };
 737             if new_parent.kind.get() != NormalModuleKind {
 738                 modifiers = modifiers & !DefModifiers::IMPORTABLE;
 739             }
 740             child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 741           }
 742           DefTrait(def_id) => {
 743               debug!("(building reduced graph for external \
 744                       crate) building type {}", final_ident);
 745
 746               // If this is a trait, add all the trait item names to the trait
 747               // info.
 748
 749               let trait_item_def_ids =
 750                 csearch::get_trait_item_def_ids(&self.session.cstore, def_id);
 751               for trait_item_def in &trait_item_def_ids {
 752                   let trait_item_name = csearch::get_trait_name(&self.session.cstore,
 753                                                                 trait_item_def.def_id());
 754
 755                   debug!("(building reduced graph for external crate) ... \
 756                           adding trait item '{}'",
 757                          token::get_name(trait_item_name));
 758
 759                   self.trait_item_map.insert((trait_item_name, def_id),
 760                                              trait_item_def.def_id());
 761
 762                   if is_exported {
 763                       self.external_exports.insert(trait_item_def.def_id());
 764                   }
 765               }
 766
 767               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 768
 769               // Define a module if necessary.
 770               let parent_link = self.get_parent_link(new_parent, name);
 771               child_name_bindings.set_module_kind(parent_link,
 772                                                   Some(def_id),
 773                                                   TraitModuleKind,
 774                                                   true,
 775                                                   is_public,
 776                                                   DUMMY_SP)
 777           }
 778           DefTy(..) | DefAssociatedTy(..) => {
 779               debug!("(building reduced graph for external \
 780                       crate) building type {}", final_ident);
 781
 782               child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 783           }
 784           DefStruct(def_id) => {
 785             debug!("(building reduced graph for external \
 786                     crate) building type and value for {}",
 787                    final_ident);
 788             child_name_bindings.define_type(def, DUMMY_SP, modifiers);
 789             let fields = csearch::get_struct_fields(&self.session.cstore, def_id).iter().map(|f| {
 790                 f.name
 791             }).collect::<Vec<_>>();
 792
 793             if fields.is_empty() {
 794                 child_name_bindings.define_value(def, DUMMY_SP, modifiers);
 795             }
 796
 797             // Record the def ID and fields of this struct.
 798             self.structs.insert(def_id, fields);
 799           }
 800           DefLocal(..) | DefPrimTy(..) | DefTyParam(..) |
 801           DefUse(..) | DefUpvar(..) | DefRegion(..) |
 802           DefLabel(..) | DefSelfTy(..) => {
 803             panic!("didn't expect `{:?}`", def);
 804           }
 805         }
 806     }
 807
 808     /// Builds the reduced graph for a single item in an external crate.
 809     fn build_reduced_graph_for_external_crate_def(&mut self,
 810                                                   root: &Rc<Module>,
 811                                                   def_like: DefLike,
 812                                                   name: Name,
 813                                                   def_visibility: Visibility) {
 814         match def_like {
 815             DlDef(def) => {
 816                 // Add the new child item, if necessary.
 817                 match def {
 818                     DefForeignMod(def_id) => {
 819                         // Foreign modules have no names. Recur and populate
 820                         // eagerly.
 821                         csearch::each_child_of_item(&self.session.cstore,
 822                                                     def_id,
 823                                                     |def_like,
 824                                                      child_name,
 825                                                      vis| {
 826                             self.build_reduced_graph_for_external_crate_def(
 827                                 root,
 828                                 def_like,
 829                                 child_name,
 830                                 vis)
 831                         });
 832                     }
 833                     _ => {
 834                         let child_name_bindings =
 835                             self.add_child(name,
 836                                            root,
 837                                            OverwriteDuplicates,
 838                                            DUMMY_SP);
 839
 840                         self.handle_external_def(def,
 841                                                  def_visibility,
 842                                                  &*child_name_bindings,
 843                                                  &token::get_name(name),
 844                                                  name,
 845                                                  root);
 846                     }
 847                 }
 848             }
 849             DlImpl(_) => {
 850                 debug!("(building reduced graph for external crate) \
 851                         ignoring impl");
 852             }
 853             DlField => {
 854                 debug!("(building reduced graph for external crate) \
 855                         ignoring field");
 856             }
 857         }
 858     }
 859
 860     /// Builds the reduced graph rooted at the given external module.
 861     fn populate_external_module(&mut self, module: &Rc<Module>) {
 862         debug!("(populating external module) attempting to populate {}",
 863                module_to_string(&**module));
 864
 865         let def_id = match module.def_id.get() {
 866             None => {
 867                 debug!("(populating external module) ... no def ID!");
 868                 return
 869             }
 870             Some(def_id) => def_id,
 871         };
 872
 873         csearch::each_child_of_item(&self.session.cstore,
 874                                     def_id,
 875                                     |def_like, child_name, visibility| {
 876             debug!("(populating external module) ... found ident: {}",
 877                    token::get_name(child_name));
 878             self.build_reduced_graph_for_external_crate_def(module,
 879                                                             def_like,
 880                                                             child_name,
 881                                                             visibility)
 882         });
 883         module.populated.set(true)
 884     }
 885
 886     /// Ensures that the reduced graph rooted at the given external module
 887     /// is built, building it if it is not.
 888     fn populate_module_if_necessary(&mut self, module: &Rc<Module>) {
 889         if !module.populated.get() {
 890             self.populate_external_module(module)
 891         }
 892         assert!(module.populated.get())
 893     }
 894
 895     /// Builds the reduced graph rooted at the 'use' directive for an external
 896     /// crate.
 897     fn build_reduced_graph_for_external_crate(&mut self, root: &Rc<Module>) {
 898         csearch::each_top_level_item_of_crate(&self.session.cstore,
 899                                               root.def_id
 900                                                   .get()
 901                                                   .unwrap()
 902                                                   .krate,
 903                                               |def_like, name, visibility| {
 904             self.build_reduced_graph_for_external_crate_def(root, def_like, name, visibility)
 905         });
 906     }
 907
 908     /// Creates and adds an import directive to the given module.
 909     fn build_import_directive(&mut self,
 910                               module_: &Module,
 911                               module_path: Vec<Name>,
 912                               subclass: ImportDirectiveSubclass,
 913                               span: Span,
 914                               id: NodeId,
 915                               is_public: bool,
 916                               shadowable: Shadowable) {
 917         module_.imports.borrow_mut().push(ImportDirective::new(module_path,
 918                                                                subclass,
 919                                                                span,
 920                                                                id,
 921                                                                is_public,
 922                                                                shadowable));
 923         self.unresolved_imports += 1;
 924         // Bump the reference count on the name. Or, if this is a glob, set
 925         // the appropriate flag.
 926
 927         match subclass {
 928             SingleImport(target, _) => {
 929                 debug!("(building import directive) building import directive: {}::{}",
 930                        names_to_string(&module_.imports.borrow().last().unwrap().module_path),
 931                        token::get_name(target));
 932
 933                 let mut import_resolutions = module_.import_resolutions.borrow_mut();
 934                 match import_resolutions.get_mut(&target) {
 935                     Some(resolution) => {
 936                         debug!("(building import directive) bumping reference");
 937                         resolution.outstanding_references += 1;
 938
 939                         // the source of this name is different now
 940                         resolution.type_id = id;
 941                         resolution.value_id = id;
 942                         resolution.is_public = is_public;
 943                         return;
 944                     }
 945                     None => {}
 946                 }
 947                 debug!("(building import directive) creating new");
 948                 let mut resolution = ImportResolution::new(id, is_public);
 949                 resolution.outstanding_references = 1;
 950                 import_resolutions.insert(target, resolution);
 951             }
 952             GlobImport => {
 953                 // Set the glob flag. This tells us that we don't know the
 954                 // module's exports ahead of time.
 955
 956                 module_.glob_count.set(module_.glob_count.get() + 1);
 957             }
 958         }
 959     }
 960 }
 961
 962 struct BuildReducedGraphVisitor<'a, 'b:'a, 'tcx:'b> {
 963     builder: GraphBuilder<'a, 'b, 'tcx>,
 964     parent: Rc<Module>
 965 }
 966
 967 impl<'a, 'b, 'v, 'tcx> Visitor<'v> for BuildReducedGraphVisitor<'a, 'b, 'tcx> {
 968     fn visit_item(&mut self, item: &Item) {
 969         let p = self.builder.build_reduced_graph_for_item(item, &self.parent);
 970         let old_parent = replace(&mut self.parent, p);
 971         visit::walk_item(self, item);
 972         self.parent = old_parent;
 973     }
 974
 975     fn visit_foreign_item(&mut self, foreign_item: &ForeignItem) {
 976         self.builder.build_reduced_graph_for_foreign_item(foreign_item, &self.parent);
 977     }
 978
 979     fn visit_block(&mut self, block: &Block) {
 980         let np = self.builder.build_reduced_graph_for_block(block, &self.parent);
 981         let old_parent = replace(&mut self.parent, np);
 982         visit::walk_block(self, block);
 983         self.parent = old_parent;
 984     }
 985 }
 986
 987 pub fn build_reduced_graph(resolver: &mut Resolver, krate: &ast::Crate) {
 988     GraphBuilder {
 989         resolver: resolver
 990     }.build_reduced_graph(krate);
 991 }
 992
 993 pub fn populate_module_if_necessary(resolver: &mut Resolver, module: &Rc<Module>) {
 994     GraphBuilder {
 995         resolver: resolver
 996     }.populate_module_if_necessary(module);
 997 }